U.S. patent number 8,944,403 [Application Number 13/553,671] was granted by the patent office on 2015-02-03 for blowout preventer with pressure-isolated operating piston assembly.
This patent grant is currently assigned to Cameron International Corporation. The grantee listed for this patent is Charles E. Gibbs, Johnny E. Jurena, David J. McWhorter, Steven F. Shimonek. Invention is credited to Charles E. Gibbs, Johnny E. Jurena, David J. McWhorter, Steven F. Shimonek.
United States Patent |
8,944,403 |
Jurena , et al. |
February 3, 2015 |
Blowout preventer with pressure-isolated operating piston
assembly
Abstract
A ram-type blowout preventer including an operating piston
assembly isolated from wellbore pressure effects is provided. In
one embodiment, a blowout preventer includes piston coupled to a
ram by a connecting rod, and the connecting rod is inserted into a
recess in the ram. A pressure-isolating seal may be provided in the
recess between the connecting rod and the ram to isolate the end of
the connecting rod within the recess from wellbore pressure in the
blowout preventer. Additional systems, devices, and methods are
also disclosed.
Inventors: |
Jurena; Johnny E. (Cypress,
TX), McWhorter; David J. (Pinehurst, TX), Gibbs; Charles
E. (Stafford, TX), Shimonek; Steven F. (League City,
TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Jurena; Johnny E.
McWhorter; David J.
Gibbs; Charles E.
Shimonek; Steven F. |
Cypress
Pinehurst
Stafford
League City |
TX
TX
TX
TX |
US
US
US
US |
|
|
Assignee: |
Cameron International
Corporation (Houston, TX)
|
Family
ID: |
49945771 |
Appl.
No.: |
13/553,671 |
Filed: |
July 19, 2012 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140021381 A1 |
Jan 23, 2014 |
|
Current U.S.
Class: |
251/1.3;
166/85.4 |
Current CPC
Class: |
F16K
51/00 (20130101); E21B 33/063 (20130101); E21B
33/062 (20130101); E21B 33/061 (20130101); Y10T
29/49412 (20150115); Y10T 137/0491 (20150401) |
Current International
Class: |
E21B
33/06 (20060101) |
Field of
Search: |
;251/1.1,1.2,1.3
;166/85.4,363,364 ;277/324,637,638,342 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Copenheaver, International Search Report and Written Opinion for
PCT/US2013/051004, mailed Dec. 23, 2013. cited by
applicant.
|
Primary Examiner: Bastianelli; John
Assistant Examiner: Rost; Andrew J
Attorney, Agent or Firm: Eubanks PLLC
Claims
The invention claimed is:
1. A system comprising: a blowout preventer including: a hollow
body; a ram disposed in the hollow body; and a bonnet assembly
coupled to the hollow body, the bonnet assembly including a piston
and a connecting rod that connects the piston to the ram to enable
the piston to drive the ram within the hollow body, wherein the
connecting rod includes an end face received by the ram and the
connecting rod is coupled to the ram with a pressure-isolating
seal, the pressure-isolating seal isolates the end face of the
connecting rod received by the ram from wellbore pressure within
the blowout preventer, and the ram, connecting rod, and
pressure-isolating seal enable pressure within a pressure-isolated
region between the end face of the connecting rod and the ram to be
maintained below wellbore pressure within the blowout preventer
when the ram is in a closed position in the hollow body.
2. The system of claim 1, comprising a locking assembly coupled to
the bonnet assembly, the locking assembly including a wedge lock
that enables the ram to be maintained in the closed position in the
hollow body regardless of the level of hydraulic pressure on the
piston.
3. The system of claim 1, comprising a relief path enabling fluid
to exit the pressure-isolated region between the end face of the
connecting rod and the ram to reduce the pressure within the
pressure-isolated region.
4. The system of claim 3, wherein the relief path extends from the
pressure-isolated region through the connecting rod.
5. The system of claim 4, wherein the relief path extends from the
pressure-isolated region to a slack chamber within the bonnet
assembly.
6. The system of claim 3, wherein the relief path extends from the
pressure-isolated region through the ram.
7. The system of claim 1, wherein the ram is a pipe ram configured
to seal against a pipe in the hollow body.
8. The system of claim 1, wherein: the ram includes a recess having
a threaded surface; and the connecting rod is coupled to the ram
with a pressure-isolating seal and with a threaded retaining nut
that is positioned about the connecting rod and is in engagement
with the threaded surface of the recess.
9. A system comprising: a connecting rod; a ram block including a
recess formed in an end face of the ram block to enable receipt of
the connecting rod within the recess, wherein the recess includes a
threaded surface; and a threaded retaining nut configured to be
positioned about the connecting rod and to engage the threaded
surface of the recess; wherein the connecting rod and the ram block
are constructed to allow the connecting rod to engage the recess by
aligning the ram block with the longitudinal axis of the connecting
rod and moving the connecting rod and the ram block together along
the longitudinal axis such that the connecting rod enters the
recess and into the ram block from the end face; the connecting rod
and the ram block are assembled to one another such that the
connecting rod is positioned within the recess of the ram block;
the system further comprises a seal between the connecting rod and
the ram block within the recess, wherein the seal isolates an end
face of the connecting rod within the recess from pressure at the
end face of the ram block; and the seal is disposed about the
connecting rod between the threaded retaining nut with an exterior
threaded surface and an additional retaining nut that is threaded
onto the connecting rod via an interior threaded surface of the
additional retaining nut.
10. The system of claim 9, comprising a spacer also disposed about
the connecting rod between the threaded retaining nut and the
additional retaining nut, wherein the spacer is positioned adjacent
to the seal.
11. The system of claim 9, wherein at least one of the ram block or
the connecting rod includes a relief path that enables fluid to
escape from a portion of the recess that is between the seal and
the bottom of the recess.
12. A system comprising: a ram block including a recess formed in
an end face of the ram block; a connecting rod coupled to the ram
block via a threaded retaining nut having an exterior threaded
surface, wherein the threaded retaining nut is threaded into the
recess of the ram block; and a seal disposed within the recess
between the connecting rod and the ram block, wherein the seal is
disposed about the connecting rod between the threaded retaining
nut with the exterior threaded surface and an additional retaining
nut that is threaded onto the connecting rod via an interior
threaded surface of the additional retaining nut.
Description
BACKGROUND
This section is intended to introduce the reader to various aspects
of art that may be related to various aspects of the presently
described embodiments. This discussion is believed to be helpful in
providing the reader with background information to facilitate a
better understanding of the various aspects of the present
embodiments. Accordingly, it should be understood that these
statements are to be read in this light, and not as admissions of
prior art.
In order to meet consumer and industrial demand for natural
resources, companies often invest significant amounts of time and
money in finding and extracting oil, natural gas, and other
subterranean resources from the earth. Particularly, once a desired
subterranean resource such as oil or natural gas is discovered,
drilling and production systems are often employed to access and
extract the resource. These systems may be located onshore or
offshore depending on the location of a desired resource. Further,
such systems generally include a wellhead assembly through which
the resource is extracted. These wellhead assemblies may include a
wide variety of components, such as various casings, valves, fluid
conduits, and the like, that control drilling or extraction
operations.
More particularly, wellhead assemblies often include a blowout
preventer, such as a ram-type blowout preventer that uses one or
more pairs of opposing rams that press against one another to
restrict flow of fluid through the blowout preventer. The rams
typically include main bodies (or ram blocks) that receive sealing
elements (or ram packers) that press together when a pair of
opposing rams close against one another. Often, the rams are driven
into and out of a main bore of a blowout preventer by operating
pistons coupled to the rams by connecting rods. In a common design,
a ram block includes a slot for receiving a button on the end of a
connecting rod, which allows the operating piston and connecting
rod to push and pull the ram block within the blowout
preventer.
SUMMARY
Certain aspects of some embodiments disclosed herein are set forth
below. It should be understood that these aspects are presented
merely to provide the reader with a brief summary of certain forms
the invention might take and that these aspects are not intended to
limit the scope of the invention. Indeed, the invention may
encompass a variety of aspects that may not be set forth below.
Embodiments of the present disclosure generally relate to systems
having rams and operating piston assemblies in which the operating
piston assemblies are isolated from certain pressure effects in the
systems. More specifically, in some embodiments blowout preventers
include operating piston assemblies with connecting rods coupled to
rams and have seals between the connecting rods and the rams that
isolate end faces of the connecting rods from wellbore pressure
within the blowout preventer. This isolation may eliminate
retraction forces that would otherwise be applied to the connecting
rods by the wellbore pressure when the rams are closed at pressure,
thereby decreasing forces transferred to wedge lock mechanisms that
hold the rams in the closed position and increasing system
efficiency. This isolation may also reduce the wellbore assist
effect on the ram assemblies when closed at pressure, thereby
increasing sealing fatigue life. In one embodiment, rather than
being received laterally in a slot open to both an end face and a
side of the ram, the connecting rod is threaded into a recess in
the end face of the ram. Additionally, some embodiments also
include relief paths that allow fluid within pressure-isolated
regions in recesses of the rams to escape.
Various refinements of the features noted above may exist in
relation to various aspects of the present embodiments. Further
features may also be incorporated in these various aspects as well.
These refinements and additional features may exist individually or
in any combination. For instance, various features discussed below
in relation to one or more of the illustrated embodiments may be
incorporated into any of the above-described aspects of the present
disclosure alone or in any combination. Again, the brief summary
presented above is intended only to familiarize the reader with
certain aspects and contexts of some embodiments without limitation
to the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of certain
embodiments will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
FIG. 1 is a perspective view of a blowout preventer having a pair
of rams that may be extended into a bore of the blowout preventer
to restrict flow through the bore in accordance with an embodiment
of the present disclosure;
FIG. 2 is a vertical cross-section of the blowout preventer of FIG.
1, depicting operating piston assemblies coupled to rams in
accordance with one embodiment;
FIG. 3 is a horizontal cross-section of the blowout preventer of
FIG. 1 also depicting operating piston assemblies coupled to rams
and wedge lock mechanisms that may be engaged to hold the rams in a
closed position;
FIGS. 4 and 5 depict a ram of the blowout preventer of FIG. 1 in
accordance with one embodiment;
FIG. 6 is an exploded view illustrating a connecting rod with the
ram of FIGS. 4 and 5 in accordance with one embodiment in which the
connecting rod may be coupled to the ram by inserting the
connecting rod into a recess formed in an end face of the ram;
FIG. 7 is a detail view of the portion of the blowout preventer
generally enclosed by the line 7-7 in FIG. 2 and depicts a
connecting rod and ram assembly in which an end of the connecting
rod in a ram is isolated from pressure about the connecting rod
behind the ram in the blowout preventer;
FIG. 8 is a detail view of the portion of the blowout preventer
generally enclosed by line 8-8 in FIG. 3 and depicts the connecting
rod and ram assembly of FIG. 7 with a relief path in the connecting
rod and a piston for fluid to pass from the pressure-isolated
region at the end of the connecting rod;
FIG. 9 is a further detail view of a portion of the blowout
preventer generally enclosed by line 9-9 in FIG. 7, which more
clearly illustrates a sealing assembly between the connecting rod
and the ram that isolates an end of the connecting rod from
wellbore pressure in accordance with one embodiment;
FIG. 10 is a horizontal cross-section of a blowout preventer having
pressure-isolating seals between connecting rods and rams, as well
as relief paths through the rams to allow the egress of fluid from
the pressure-isolated regions about the ends of the connecting rods
in the rams, in accordance with one embodiment;
FIG. 11 depicts a vertical cross-section of the blowout preventer
of FIG. 10; and
FIG. 12 is a detail view of the portion of the blowout preventer
generally enclosed by line 12-12 in FIG. 10.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
One or more specific embodiments of the present disclosure will be
described below. In an effort to provide a concise description of
these embodiments, all features of an actual implementation may not
be described in the specification. It should be appreciated that in
the development of any such actual implementation, as in any
engineering or design project, numerous implementation-specific
decisions must be made to achieve the developers' specific goals,
such as compliance with system-related and business-related
constraints, which may vary from one implementation to another.
Moreover, it should be appreciated that such a development effort
might be complex and time consuming, but would nevertheless be a
routine undertaking of design, fabrication, and manufacture for
those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments, the articles "a,"
"an," "the," and "said" are intended to mean that there are one or
more of the elements. The terms "comprising," "including," and
"having" are intended to be inclusive and mean that there may be
additional elements other than the listed elements. Moreover, any
use of "top," "bottom," "above," "below," other directional terms,
and variations of these terms is made for convenience, but does not
require any particular orientation of the components.
Turning now to the drawings, a blowout preventer 10 is illustrated
in FIG. 1 by way of example. The depicted blowout preventer 10
includes a hollow main body 12 and a bore 14 that enables passage
of fluid or tubular members through the blowout preventer 10. As
will be appreciated, the blowout preventer 10 may be coupled to
other equipment that facilitates natural resource production. For
instance, production equipment or other components may be attached
to the top of the blowout preventer 10 via fasteners 16 (provided
in the form of studs and nuts in FIG. 1) and the blowout preventer
10 may be attached to a wellhead or spool via flange 18 and
additional fasteners.
Bonnet assemblies 20 secured to the main body 12 include various
components that facilitate control of sealing rams disposed in the
blowout preventer 10, and locking assemblies 22 enable the sealing
rams to be locked in a closed position. Particularly, as
illustrated in the cross-sections of FIGS. 2 and 3, the blowout
preventer 10 includes a pair of rams 24 actuated by operating
piston assemblies that include pistons 26 and connecting rods 28.
In operation, a force (e.g., from hydraulic pressure) may be
applied to the operating pistons 26 to drive the rams 24 into the
bore 14 of the blowout preventer 10. The rams 24 include sealing
elements 30, also known as ram packers, that cooperate with one
another when driven together to seal the bore 14 and inhibit flow
through the blowout preventer 10. When these the rams 24 are moved
into the closed position to seal the bore 14, wedge locks 34 (FIG.
3) of the locking assemblies 22 may be moved into position behind
tail rods of the pistons 26 to hold the rams 24 in the closed
position. This allows the hydraulic pressure acting on the pistons
26 to be reduced (from the closing pressure) while still
maintaining the rams 24 in the closed position.
In the embodiment depicted in FIGS. 2 and 3, the rams 24 are
provided in the form of pipe rams configured to seal against one
another and about pipe 32 (or another tubular member) in the bore
14. A more detailed example of a ram 24 in the form of a pipe ram
is illustrated in FIGS. 4 and 5 and described further below. But it
is first noted that rams 24 may be of any desired size and may vary
depending on the intended application. For example, different pipe
rams 24 may be sized for use with blowout preventers having various
bore diameters and the ram packers 30 may be selected according to
the diameter of the pipe about which the ram packers 30 are
intended to seal. In other embodiments, the rams 24 include
variable-bore pipe rams that may be used to seal around pipes
having a range of diameters (e.g., 27/8 to 4 inches, 27/8 to 5
inches, or 31/2 to 57/8 inches). And although rams 24 are depicted
as pipe rams in FIGS. 2-5, still other embodiments could include
different rams (e.g., blind rams or shear rams).
Again with reference to FIGS. 4 and 5, the depicted ram 24 includes
a top seal 36 in addition to the ram packer 30. The top seal 36
abuts the surface of the main body 12 above the ram 24 in FIG. 2
and, with the ram packer 30, seals upper and lower portions of the
bore 14 from one another. The ram packer 30 and top seal 36 are
formed of any suitable material, such as an elastomer. The ram 24
may include latching features to mate with corresponding features
of an opposing ram, such as the angled features of the ram above
and below the front face of the ram packer 30 in FIG. 4. And as
depicted in FIG. 5, the end face 40 of the ram 24 includes a recess
42 having a threaded interior surface 44 and a bottom 48 for
receiving an end of the connecting rod 28, although the ram 24 and
the connecting rod 28 may be coupled differently (e.g., a snap
ring) in other embodiments.
In some embodiments, such as that of FIG. 5, the recess 42 is
formed entirely in the end face 40 without extending to a lateral
edge or side 46 of the ram 24. In such an arrangement, the recess
42 may be aligned with the longitudinal axis of the connecting rod
28, which may then be coupled to the ram 24 by inserting the
connecting rod 28 into the recess 42 along the longitudinal axis.
In one embodiment generally shown in FIG. 6, an end of the
connecting rod 28 includes a sealing assembly that enables the
connecting rod 28 to be secured to the ram 24 via the recess 42.
Particularly, the depicted sealing assembly includes (in order
along the connecting rod 28) a retaining nut 50, a seal 52, a
spacer 54, and another retaining nut 56. The retaining nut 50
includes a threaded exterior surface configured to mate with the
threaded interior surface 44 of the recess 42. As a result, the
connecting rod 28 may be threaded into the recess 42 and retained
within the ram 24 by mating engagement of the threads of the
surface 44 and the retaining nut 50. The retaining nut 56 includes
a threaded interior surface and is threaded onto the end of the
connecting rod 28 to retain the seal 52 and the spacer 54 on the
connecting rod 28.
The seal 52 may be formed of any suitable material, such as an
elastomer. Once installed in the recess 42, the seal 52 seals
against the bore of the recess 42 and isolates a region along an
end face of the connecting rod 28 in the recess 42 from pressure on
the other side of the seal 52 (e.g., pressure at the end face 40 of
the ram 24). Such isolation reduces retraction force on the
connecting rod 28 when the ram 24 is actuated into a sealing
position. Particularly, when the rams 24 of the blowout preventer
10 are closed, wellbore pressure in the blowout preventer 10 (e.g.,
within the bore 14 below the rams 24 in FIG. 2) is communicated to
regions behind the rams 24 (i.e., between the bonnet assemblies 20
and the end faces 40 of the rams 24). Having the wellbore pressure
behind the rams 24 when in the closed position provides a "wellbore
assist effect" in that the wellbore pressure applies forces against
the end faces 40 of the rams 24 toward the bore 14 of the blowout
preventer 10.
While this wellbore assist effect may help keep rams of a blowout
preventer closed at pressure, left unchecked this same wellbore
pressure would also apply a retraction force to the end face of a
connecting rod in a ram, which in essence operates to try to push
the connecting rod away from the bore of the blowout preventer and
back into a bonnet assembly. If the operating pistons are not
locked into place, a sufficiently large retraction force could
cause the rams to open or leak. Also, in arrangements including a
connecting rod having a button received in a slot of a ram, a
sufficiently large retraction force could damage the button or the
slot.
But unlike previous arrangements susceptible to this retraction
force, present embodiments include a seal (such as seal 52) that
isolates the operating piston assembly, and particularly the end
face of the connecting rod in the ram, from wellbore pressure. This
isolation reduces or eliminates the retraction force on the end
face of the connecting rod from the wellbore pressure. The
reduction of the retraction force on the connecting rod increases
the closing ratio of the actuating piston and ram assembly,
resulting in more efficient operation of the operating piston. And
this increase in efficiency enables the system to be used at
greater maximum pressures or to be reduced in size while handling
the same maximum pressure as before. While the present
pressure-isolated arrangement may be used in blowout preventers (or
other sealing systems) of any rated pressure, this arrangement may
find particular use in blowout preventers with higher pressure
ratings, such as 20,000 psi, 25,000 psi, 30,000 psi, or even
greater.
One ram 24 and its associated connecting rod 28 installed in the
blowout preventer 10 are depicted in FIGS. 7-9 as an example. As
shown in the cross-sections of FIGS. 7 and 8, the connecting rod 28
is coupled to the ram 24 on one end and to the piston 26 on the
other end. In this embodiment, the connecting rod 28 is threaded
into the piston 26. And in addition to the seal 52, other
pressure-isolating seals are provided throughout the blowout
preventer 10, such as seals 60 along the connecting rod 28.
As noted above, the inclusion of a pressure-isolating seal 52
between the connecting rod 28 and the ram 24 isolates the operating
piston assembly from wellbore pressure effects, reducing or
eliminating retracting pressure on the end face 70 (FIG. 9) of the
connecting rod in the recess 42. The seal 52 may have any suitable
configuration. For instance, in FIG. 9 the seal 52 is depicted as a
two-piece seal with an inner seal component 74 and an outer seal
component 76. In other embodiments the seal may have a different
construction, such as a single-component seal. Additionally, in
some embodiments the portion of the recess 42 abutting the seal 52
may have a finish or an inlay that facilitates sealing or reduces
wear.
But even with the pressure-isolating seal 52, it is possible in
some instances that pressurized fluid may be present between the
end face 70 and the bottom 48 of the recess 42. Consequently, in
some embodiments the blowout preventer 10 includes a relief path
(which may also be referred to as a vent path) leading away from
the portion of the recess isolated by the seal 52 to allow fluid in
the portion to escape from the recess 42. In the blowout preventer
of FIGS. 7-9, this relief path includes passageways or conduits 62
and 64 through the connecting rod 28 and the piston 26.
Particularly, rather than being trapped, fluid in the recess 42
behind the seal 52 (e.g., between the end face 70 of the connecting
rod 28 and the bottom 48 of the recess 42) may escape the recess 42
by passing into an opening of conduit 62 in the end face 70 of the
connecting rod 28 and through the conduit 62 to the conduit 64 of
the operating piston 26. And in the present embodiment, the conduit
64 leads to a chamber 66 of the bonnet assembly 20 (which may be
referred to as a "slack" chamber for the piston 26), allowing fluid
to pass from the base of the recess 42 to the chamber 66.
A blowout preventer 10 of another embodiment is depicted in the
cross-sections provided in FIGS. 10-12. In these figures, the
blowout preventer 10 includes different relief paths from the
recesses 42, but is otherwise similar to the blowout preventer
depicted in the previous figures. More specifically, rather than
having relief paths from the recesses 42 that pass through the
connecting rods 28, the pistons 26, and into slack chambers 66 in
the bonnet assemblies 20, the blowout preventer 10 of FIGS. 10-12
includes relief paths, in the form of passageways or conduits 80,
that extend through the rams 24 themselves. In this embodiment,
fluid passes from the bottom of the recesses 42 behind the seals 52
of each ram 24, through the conduits 80, and into the bore 14 of
the main body 12 of the blowout preventer.
While the aspects of the present disclosure may be susceptible to
various modifications and alternative forms, specific embodiments
have been shown by way of example in the drawings and have been
described in detail herein. But it should be understood that the
invention is not intended to be limited to the particular forms
disclosed. Rather, the invention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope
of the invention as defined by the following appended claims.
* * * * *